The invention relates generally to semiconductor integrated circuits, and more particularly, to an apparatus and method for etching a semiconductor integrated circuit such as on a spherical-shaped semiconductor device.
Conventional integrated circuit devices, or "chips," are formed from a flat surface semiconductor wafer. The semiconductor wafer is first manufactured in a semiconductor material manufacturing facility and is then provided to a fabrication facility. At the latter facility, several processing operations are performed on the semiconductor wafer surface.
One common processing operation is etching. Conventionally, whole wafers are completely coated with a layer or layers of various materials such as silicon nitride, silicon dioxide, or a metal. The unwanted material is then selectively removed by etching through a mask, thereby leaving, for example, selectively removed by etching through a mask, thereby leaving, for example, various patterns and holes in a thermal oxide where diffusions are to be made. For another example, etching can be used to create long stripes of aluminum for electrical interconnects between individual circuit elements. In addition, various patterns must sometimes be etched directly into the semiconductor surface. Examples include: circular holes or short grooves where trench capacitors are to be made in silicon; mesas that are required in the silicon dielectric isolation process; and small, flat depressions in GaAs where the gate metal is to be deposited.
While most etching processes use a mask, a few procedures do not involve any local masking. These procedures include etching whole semiconductor slices to remove damage and/or to polish the surface, and etching slices or chips to delineate crystallographic defects. In addition, before the advent of planar technology, a variety of germanium and silicon etching steps were used for removing damage from junctions.
There are many different kinds of etching processes. One such type is plasma etching. Plasma etching, and combination plasma/reactive ion etching, are performed in a low-pressure gaseous plasma, and are most commonly used in fine-geometry applications. Plasma etching generally involves fewer safety hazards and spent chemical disposal problems, but the additional cost of plasma equipment is a deterrent to its use when fine-line definition is not necessary.
In U.S. Pat. No. 5,955,776, a method and apparatus for manufacturing spherical-shaped semiconductor integrated circuit devices is disclosed. It is desired to provide an apparatus and method for performing plasma etching processes on a spherical-shaped device to create the integrated circuit thereon.